1. Chemical and Biological Indicators
Water Quality
Chemical and Biological Indicators

2. Why is water quality important?
Human health: drinking water
Fisheries
Water for industry and
agriculture
Aesthetic reasons
Species habitat
Water for recreation
(swimming, fishing, boating)
Ask students to brainstorm why water quality is important to them

3. What types of tests do we use to measure water quality?
Dissolved oxygen
Nitrogen (usually nitrate-nitrogen) pH
Macroinvertebrates
Phosphorus (usually phosphate-phosphorus)
Alkalinity
Conductivity
Chloride
Salinity
Suspended solids
Fecal coliform bacteria
There are a large number of different types of water quality tests

4. Dissolved Oxygen
The presence of oxygen gas molecules (O2) in the water.
Why is it important?
The oxygen in H2O is not dissolved oxygen.
Dissolved oxygen is often the most common, and most important, water quality test. It will give you an immediate indication of the health of the aquatic system.
What’s coming out of the diffuser?

5. Dissolved Oxygen How does oxygen get into the water?
-diffusion from the surrounding air
-during the process of photosynthesis

6. DO levels are affected by:
Altitude
Temperature
Speed of water movement (dams as well as natural differences and tides)
Addition of wastes
Vegetation

7. Hudson River near Newburgh, NY, summer
Hudson River near Warrensburg, NY, winter
Cold water holds more DO than warm water; fast moving water generally has more oxygen than slower moving waters. However, plant growth (unknown from these images) will also affect DO levels.
Which do you think has more DO: the stream on the left or the stream on the right? Why? What else do you need to know?

8. Different Organisms Require Different Amounts of DO
Trout and salmon require high amounts of dissolved oxygen, as do most fish larvae
Trout do not do well in waters below 4-5 ppm.
Carp and catfish can survive with much less.

9. How do Humans Affect the Amount of DO in the Water?
Addition of oxygen-consuming organic wastes

10. Changing the Flow of the Water
Which dam is this?
The Croton Dam

11. Activities That Raise the Water Temperature
Allowing vegetation to grow along shorelines will reduce the water temperature.
Riparian zone vegetation, power plant cooling
Source:

12. pH The measure of the acidity of a solution
Acids produce H+ (hydrogen ions)
Bases produce OH- (hydroxide ions)

13. Why is pH important?
If the pH is too low, it could indicate pollution from acid rain
Acid rain can kill insects and other organisms, and harms vegetation, often killing forests (especially in high altitude areas because of acidic fog)
Photo courtesy of C. Harris

14. How is pH measured? -pH is measured on a scale of 0 to 14.
-A solution with equal hydrogen and hydroxide ions would have a pH of 7
-What would the pH of a solution be that had more hydrogen than hydroxide ions?
-A decrease of one unit on the pH scale is the result of a 10 fold increase in hydrogen ions.
Drawing by J. Jenkins

15. basic
neutral
The photo is from the Adirondacks, which generally suffers from high levels of acid rain.
acidic

16. How Does pH Affect a River?
It changes the availability of different nutrients and metals in the water, making it hard for some animals to survive
Metals that leach from the soils when pH changes especially affect immature stages of aquatic insects and fish
Fish larvae exposed to biotoxins that cause morphological abnormalities.

17. What Causes a pH Change? Atmospheric deposition (acid rain)
Surrounding rocks and soils
Wastewater discharges from business and industry
Acid mine drainage

18. Acid Rain in U.S.

19. Nitrogen Pollution Do you contain nitrogen?
Does the air contain nitrogen?
What about plants and animals?
Everything around us contains nitrogen

20. Nitrogen …so what? Plants and animals need nitrogen
But…there can be too much of a good thing!
Too much nitrogen results in….
There is both cultural (human) and natural eutrophication

21. Nitrogen Pollution Too much nitrogen can cause: Eutrophication
Increase in nutrients
Aquatic life suffers
Increase in plant growth
Dissolved oxygen declines as plants are decomposed

22. Nitrogen in the Hudson
Where does it come from? -human waste -acid deposition -fertilizer -agriculture: fixation and feed Where does it go?
The nitrogen from the Hudson River ends up in the Atlantic Ocean

24. Nitrogen: Why so much from the middle of the USA?
The middle of the US uses a lot of nitrogen fertilizer to grow crops

25. 1850s Iowa – beige color is prairie
1990s Iowa – beige color is prairie, gray is row crops
Source:  Compiled from Landsat Thematic Mapper satellite imagery, Iowa Dept. of Natural Resources.

26. Humans and the Nitrogen Cycle
Last 100 years: humans have more than doubled the amount of fixed nitrogen that is pumped into the atmosphere every year.
Consequences: acid rain, ground level ozone, groundwater contamination, surface water pollution, eutrophication
The map shows the amount of N deposition show as increased pH (nitrogen oxides from fossil fuel combustion)

27. Phosphorous Where does it come from? -not a gas -weathers from rock
-reuse from already present phosphorous in detritus
Why is it important?
-less abundant and available than N
-often the limiting nutrient in freshwater ecosystems

28. Phosphorus Cycle Phosphates in rocks are mined
Dissolves in water
Plants take up inorganic phosphate
We create phosphate-rich fertilizer
Organisms use organic phosphates
Decomposers convert organic waste back to inorganic P in the soil
Most of the phosphorous in the world is found in rocks (not as a gas)
It is transported by water as the rocks are broken down by weathering
Organisms use inorganic P to form bones and other important molecules
It gets passed through food chains
When the organisms die it is returned to the soil
Phosphates are major components of fertilizers.
They make plants grow, especially in aquatic ecosystems

29. Phosphorous in the Hudson
Main source: detritus
Used by plants during the growing season
Some P is lost to the ocean and some becomes buried in sediment

30. Macroinvertebrates Why do we sample invertebrates??
It’s a way to measure the health of an ecosystem’s aquatic life
Scientists usually take several samples, looking at diversity and abundance, as well as species evenness
Dobsonfly larvae (helgrammite). Photo from Cary Institute.

31. Aquatic Ecosystem Biodiversity

32. Species Diversity
Diversity differs depending on: time of year, habitat, ecosystem, sampling location, and water quality
Macroinvertebrates are one way to assess water quality, but other measurements should be taken to ensure accuracy
Students from Tabernacle Christian Academy, Poughkeepsie

33. Alkalinity
A measure of the capacity of water to neutralize (or buffer) acids
Streams with high alkalinity would be able to resist a change in pH more than a stream with low alkalinity
Alkalinity is reported as mg/L of CaCO3

34. What are the Sources of Alkalinity?
Compounds that create alkalinity include calcium carbonate, sodium bicarbonate, and calcium hydroxide.
Limestone bedrock, like that in the Hudson River, produces water with relatively high alkalinity
Photo by H. Malcom

35. Fecal coliform
Fecal coliform bacteria refers to a group of micro-organisms that live in the digestive tracts of warm-blooded animals, such as humans
Indicates: sewage or manure

36.
h20_contaminants_200/fecal_coliform_200.jpg
Health risk for humans due to disease causing bacteria/viruses (hepatitis A and typhoid fever)

37. Suspended Solids
Suspended solids is a measure of how many particles are suspended in the water
Caused by soil erosion, sewage discharge, algal growth, and movement of the water
It is often measured along with turbidity, which is faster to measure
Usually measured in mg/L
Photo courtesy of C. Harris

38. Suspended particles can clog fish gills, smother eggs of fish and aquatic insects, and reduce growth rates.
High suspended solids can decrease dissolved oxygen by blocking sunlight for plants and increasing the temperature of the water by absorbing light from the sun.
Photo: C. Harris